1. Field of the Invention
The present invention relates to the production of alkoxylated alcohols and, more particularly, to the clarification of an alkoxylated alcohol mixture produced using a calcium-based catalyst system.
2. Description of the Prior Art
Alkoxylated alcohols, e.g., ethoxylated alcohols, are well known and find wide use in a variety of products such as, for example, surfactants. Typically, these alkoxylated alcohols, which can be considered alkylene oxide adducts of alcohols, are prepared by an addition or alkoxylation reaction in which an alkylene oxide, such as ethylene oxide, is reacted under suitable conditions with an alcohol, generally a long chain, fatty alcohol. In particular, ethylene oxide adducts of aliphatic alcohols and substituted phenols having from about 8 to 20 carbon atoms, have found widespread utility as non-ionic detergent components of cleaning formulations for use in industry and in the home.
In recent years, there has been an emphasis on producing alkoxylated alcohols that have a narrow homolog distribution, such alkoxylated alcohols being commonly referred to as peaked alkoxylated alcohols. In general, due to an increased understanding of the properties to be provided by alkoxylated alcohols, greater demands have been placed on tailoring the manufacture of the alkoxylated alcohols to enhance the properties. Accordingly, efforts have been expended to provide alkoxylated products in which the distribution of the reacted alkoxide units per mole of alcohol is limited to a range in which the sought properties are enhanced.
U.S. Pat. Nos. 4,820,673 and 4,835,321 disclose catalysts and processes for producing peaked alkoxylated alcohols. In the processes disclosed in both of the aforementioned patents, both of which are incorporated herein by reference, a calcium-based catalyst system is employed, i.e., the catalyst employs a calcium compound such as calcium oxide, calcium hydroxide, or the like.
While the processes using the calcium-based catalysts disclosed in the aforementioned patents produce alkoxylated alcohols having a narrow distribution of the alkoxylation species, i.e., peaked alkoxylated alcohols, the product mixture containing the alkoxylated alcohols contain undissolved solids, primarily calcium-based in nature, that impart a haze or cloudiness to the product mixture. Not only is the haze in the product mixture undesirable from an aesthetic point of view, the undissolved solids responsible for the haze can cause processing problems. For example, when the product mixture is used to make sulfated end products, the solids forming the haze can plug filters used in the sulfation process.